Pressure density issues when using vortex flowmeters to measure gases
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Recently, an vortex flow meter in our facility has been used to measure the flow rate of dry gas. The flow rate at the inlet, as measured by a orifice flow meter, was 8000 NM3/h; after desulfurization treatment, the value measured by the vortex flow meter was slightly over 6000 standard cubic meters. The pressure at the inlet varied little, but the pressure at the outlet fluctuated significantly, ranging from 0.55 to 0.75 MPa. The parameter checks showed that the standard density inside the vortex flow meter was 0.1 kg/m3, while the operating density was 0.7 kg/m3. Is there something wrong with these settings? How should this issue be resolved?
It is recommended to implement temperature and pressure compensation; vortex flowmeters measure the volume at the current conditions, so it is advisable to add such compensation in order to convert the value to standard cubic units. Otherwise, different pressures will have varying effects on the flowmeter, especially in situations with fluctuating conditions like yours……
Well, thank you. We also want to implement pressure compensation – compensation is needed for both the inlet and outlet flows. Since the temperature doesn’t change much, there’s no need for compensation, right?
Compensating for one is also okay; it can reduce the error……
Is your system controlled by DCS? Where do you plan to place the pressure gauge transmitter on the pipe section? Do the software programs also need to be modified? Could you share the specific solution?
Wait, I didn’t see it clearly before; each gauge just needs to compensate for the pressure before its own gauge. The location of the pressure sensing point should not be too far from the gauge. Also, it’s best to have one temperature measurement; if that’s not possible, setting one value will work as well
Yes, temperature and pressure compensation is implemented through configuration within the DCS. Since different control systems have varying configurations, the configuration procedures also differ. In fact, it’s quite simple to implement this; modern DCS systems are very user-friendly, with configuration interfaces in Chinese. One just needs to call the relevant logic blocks and then download the configuration program.